Importance
The Murray and Darling Rivers have great variability in year to year flows, and their ecology is driven by large floods covering their extensive floodplains and intervening dry periods. Compared to other major river systems the in the world, the Murray-Darling is large in terms of its length and catchment area, but small and erratic in terms of discharge, and surface runoff.

Location
The Murray and Darling Rivers cross 4 Australian states and one territory, draining roughly 14% of Australia's land mass. The source of the Murray, which contributes the majority of the system’s total discharge, is in the Australian Alps. The Murray-Darling river basin is a vital source of water for the major cities of Adelaide and Canberra, but it is more than 30% arid.

Species
Despite these variable conditions, the Murray-Darling is home to abundant aquatic plant and animal life. In the Murray-Darling basin, there are around 30,000 wetlands, 12 of these are internationally recognized Ramsar sites.

The basin is known for its diversity of crayfish and freshwater snails, and is home to 16 mammal and 35 bird species that are nationally endangered.

Despite the relatively low number of endemic fish species (7 in total), it is home to flagship species such as the Silver Perch, Freshwater Catfish and the large Murray Cod all of which are in rapid decline.